Digitalisation of Railway Tunnels for Climate Change Adaptation and Enhanced Asset Circularity

Abstract

The climate change adaptation strategies for the railway tunnels project are managed by digital multidisciplinary coordination, or Building Information Modelling (BIM), and the case study is focused on the Taipei Metro (MT) Tamsui–Xinyi Line in Taiwan for the railway tunnel analysis. With increasing climate change impacts (such as flooding, earthquakes, extreme temperature, sea level rise, etc.) on railway infrastructure, BIM offers a transformative approach to enhance resilience. This research integrated six BIM dimensions (2D & 3D models, visualisation, scheduling, cost estimation, and sustainability), involved additional material information with Ansys Granta EduPack v.2021 to measure the expenditure of materials and the carbon footprint, and further applied them to propose adaptation measures for the chosen railway tunnel. This study aims to enhance actions to adapt and mitigate climate change effects on railway tunnels, thereby analysing the negative impact of weather hazards. The climate change adaptation strategies are determined based on the case study, and the integration of expenditure, planning, and greenhouse gas emissions is assessed by implementing BIM. AutoCAD Revit v.2021 and Navisworks 19.4 are the virtual simulation tools for design coordination and scheduling for climate risk assessments. The results demonstrate the feasibility of BIM in managing adaptation projects and enhancing asset circularity at the end of life, showcasing its potential for improving efficiency. This study is the world’s first to contribute to enhancing infrastructure management by implementing the advanced capabilities of BIM to develop detailed resilience strategies for railway tunnels.

1. Introduction

The implementation of Building Information Modelling (BIM) stands as the vital digital representation for overcoming the myriad challenges in infrastructure management within the Architecture, Engineering, and Construction (AEC) industry worldwide [1]. BIM adaptions enhance the comprehensiveness of operation and business aspects due to its high performance in the capability of integrated related information, stakeholder collaboration, and communication, which are inherent difficulties in traditional project management methods. Following BIM’s recent extensive growth, it presents benefits for infrastructure in leading sectors like transportation, especially railway projects [2,3]. However, persistent external factors like climate change remain a severe issue that significantly impact the resilience of these railway assets in the future. Garmabaki et al. [4] indicate that the hazards associated with unpredicted climate change result in specific difficulties (train delays, failures, incidents, etc.) for railway infrastructure, operation, and maintenance. Hence, it is imperative to develop sustainable considerations to mitigate the impacts of potential climate factors on railway infrastructure. With the many possibilities of BIM, this innovative technological approach introduces a method to direct the successful implementation of mitigation measures [5]. This research aims to evaluate the potential of BIM in managing climate change adaptation strategies for railway tunnels. To achieve this, the following objectives have been established: (1) identify the risks of climate change on railway tunnels, (2) analyse the potential impacts of climate change on railway tunnels, (3) develop climate change adaptation strategies for railway tunnels against future potential impacts, and (4) implement BIM that evaluates the time, costs, and carbon emissions resources of the climate change adaptation strategies for railway tunnels. The case study focuses on the Taipei Metro (MT) Tamsui–Xinyi Line in Taiwan for railway tunnel analysis using integrated BIM implementation and climate change adaptation strategies.

2. Literature Review

2.1. BIM Dimensions and Adoption for Railways

BIM is considered an innovative approach to traditional project management methods, and the critical factors in achieving its successful adoption include the capabilities of collaboration, commitment, and cooperation [5]. It has proven beneficial in many ways, including a better overall understanding between all the stakeholders involved in the project [1]. BIM also provides a visual representation of a physical asset, enhancing the accessibility and in-depth understanding for the involved users. Several studies by Kaewunruen et al. [2,3] also demonstrate the benefits of the general application of BIM, allowing for better performance in analysing cost and time efficiency, which leads to significant improvements in infrastructure management. Building Information Modelling (BIM) begins with developing an intelligent 3D model that simulates the digital information and enhances management throughout a project’s life cycle: documentation, planning, designing, constructing, operating, maintaining, and demolishing. The evaluation of cost and time are identified under the different dimensions beyond 3D BIM. A systematic study analysed the utilisation conditions across the world and demonstrated that industry experts agreed that 4D BIM is related to project planning and scheduling (time), and 5D BIM refers to the estimation and measurement of cost [6]. Some practitioners in the study argue that the sixth dimension of BIM represents facility management [6], but in most cases, 6D BIM usually considers the sustainability aspects for project life cycle management.

The UK BIM Maturity Model, initially developed by Bew and Richards [7], establishes a framework for categorizing the levels of BIM adoption. This model delineates the progressive integration of digital tools, methodologies, and collaborative practices, aligning BIM with international standards and guidelines across the project life cycle. Based on the Bew–Richards BIM Maturity Model,

Table 1. Description of 6D BIM maturity levels.

Classification	Description
BIM Level 0 Low Collaboration	Project information is done with 2D CAD. Files are shared as separate sources of information.
BIM Level 1 Partial Collaboration	Teams use a Common Data Environment (CDM). Data are a combination of 3D and 2D CAD.
BIM Level 2 Full Collaboration	3D modelling to develop project and produce information. Shared using a common file type, creating a unified BIM. Time (4D) and cost (5D) dimensions are available.
BIM Level 3 Full Integration	A unified BIM model via a cloud-based environment. All members can access and add information. 6D introduced for project life cycle management.

outlines the critical milestones across BIM Levels 0 to 3, specifying the dimensions associated with the various levels of integration. BIM maturity is segmented into four phases based on the degrees of collaborative integration. According to BS EN ISO 19650-1 [8], BIM maturity levels identify the integration of 4D, 5D, and 6D information into 3D BIM as Level 3, which signifies a fully integrated and collaborative model.

Railway infrastructure projects are complex yet highly valuable within the transportation industry. The robust capability of BIM seems a priority choice for digital utilisation to achieve comprehensive management in the railways sector; however, a notable decline in the level of collaboration is observed in BIM applications from the early stage phase to the end of the life cycle due to a lack of understanding of life cycle assessment [1]. Most railway projects depend primarily on traditional management practices [9]. Recent studies show impressive growth in BIM implementation for railway projects due to the increasing demands for transportation development [5]. The expansion of BIM has, therefore, enabled its utilisation on railway tunnels to be documented with specific insights into the processes. For example, BIM technology has been applied to construct an underground railway as an immediate solution to reduce traffic congestion [10]. The utilisation of AutoCAD Revit 2021.1.10 software provided efficiency in the design through 3D simulation, and the advanced integration of time constraints (4D BIM model) was analysed in Navisworks. A similar approach was conducted by Chen [11], where Navisworks 19.4 integrated the dimension of time into the BIM model, demonstrating optimal project planning to guide the subsequent production stages of the railway tunnel. Later, a detailed review of the BIM application for transport for London’s tunnel project [12] stated that they could further create 3D, 4D, and 5D models from the survey model. This new dimension of BIM contributed to accurate cost measurements, improving the life cycle management of the railway tunnel.

Railway tunnel projects have integrated 3D BIM with other dimensions for adequate time and cost management. Applying BIM to railways is a continuous improvement process [5]. In the emerging era of sustainability, future infrastructure is required to be more energy efficient [13]. According to Habib and Erziaj [14], this can be achieved by adding 6D BIM to evaluate the sustainability features. Kaewunruen et al. [2] studied the potential of 6D BIM for managing the maintenance and resilience of a railway tunnel case study through the integration of BIM (Revit) and Navisworks. The results show that the BIM model can help reach a sustainable goal by determining the carbon emissions, cost estimation, and time management for a project’s life cycle.

2.2. Railway Resilience and Climate Change Adaptation

Baker et al. [15] stated that weather-related events impact function degradation and significantly influence the vulnerability of resilience networks. The railway system’s vulnerability against climate change’s effects depends on its resilience, which refers to its ability to successfully recover from the consequences [16]. The resilience of a railway system is defined as a comprehensive system that produces effective service in normal conditions and the ability to resist and recover quickly from disruptions and disasters [17]. Facing the risks of climate change, research studies throughout the years revealed that to enhance the resilience of a railway infrastructure facing climate risks, it is necessary to engage with adaptive measures [18,19,20,21]. Therefore, Ferranti et al. [22] described climate adaptation as a process where changes are made for current and future weather-related hazards. These may include physical changes to the railway infrastructure or organisational changes to the railway management. Case studies of railways worldwide [23] highlighted the progress of adaptation strategy development within the industry, and recommendations were also extended for the adaptation measures used in the research countries of Canada, China, and Sweden. The results show recognisable variations in how each country mitigates its climate impacts, depending on the depth of awareness and available resources.

Climate change is a global phenomenon that continues to influence the transportation industry. These weather-related hazards negatively impact railway systems, causing significant problems that affect railway infrastructure, operation, and maintenance [4]. Many professionals stated that the significant effects will likely impact the future of railway projects [15]. The potential natural impacts on railways include extreme temperature changes, high precipitation on earthworks, extreme wind, and sea level rising. The increase in intensity and frequency of these weather conditions can lead to traffic disruptions from delays and the possibility of accidents, which will result in higher maintenance costs [24]. Throughout the years, multiple researchers have demonstrated an equally strong understanding of climate change’s different consequences.

Table 2. The effects of climate change on railway infrastructure.

Climate Factor	Associated Risks	Impacts on Railways
High temperature	Heatwaves, Wildfire	Track buckling, Thermal expansion
Low temperature	Snow, Ice, Frost	Tunnel icing, Rail breakage, Equipment damage
High precipitation	Flooding, Infiltration, Landslide	Slope failure, Track flooding, Water damage
Low precipitation	Drought, Shrinkage	Asset misalignment
Windstorms	Tree fall, Blown objects	Structural damage
Sea level rise	Coastal flooding	Structural damage, Tunnel flooding

provides a critical risk assessment of railway systems concerning the potential environmental factors, as derived from observations in existing studies [4,15,24,25,26,27]. The critical climate factors assessed include extreme temperatures, high and low precipitation, windstorms, and rising sea levels, and the potential impacts on the complex railway infrastructure are highlighted depending on various climate factors.

The complications include flooding, drainage system failures, poor structural support, ice formation, and limited clearance, which are common problems in railway tunnel projects [25,26]. However, the impact of these climate factors varies between geographical locations, thus requiring an in-depth climate analysis of the particular area [24,27]. Risk identification is implemented by considering the geography domain climate change assessment and developing an effective plan to reduce the likelihood of railway failures due to climate change. For example, geographic risk identification was adopted in Singapore and Malaysia’s high-speed railways to evaluate the systems’ resilience to the changing climate [28]. Closely monitoring these risks allows experts to pinpoint the risks and maintain a suitable way forward. The development of an integrated risk management approach is currently being researched to enhance future climate change risk management [4].

To summarize the relationship between climate change effects and railway adaptation, Khah et al. [29] established that considering the parameters of climate change is necessary to mitigate these environmental impacts through adaptive strategies. Moreover, Garmabaki et al. [4] recently emphasised in agreement that having a practical approach (risk awareness, identification, and assessment) is essential to achieve success in commencing these adaptation strategies for railway projects. This all-inclusive concept will be applied in our methodology stages to direct the evaluation of suitable adaptation strategies to achieve railway resilience.

2.3. Key Highlight of This Study

Climate change is inevitable, necessitating urgent adaptation strategies, particularly for existing infrastructure. Previous studies indicate that climate adaptation poses a complex management issue due to the inherent unpredictability of weather patterns. However, integrating advanced digital technologies, such as Building Information Modelling (BIM) [4], offers a pathway to enhance project management efficiency across the infrastructure life cycle through real-time updates and monitoring. Leveraging BIM and digital twin technologies to monitor adaptation measures is crucial for ensuring infrastructure safety and resilience. Effective monitoring systems like landslide detection and flood protection measures like sheet piling can strengthen the infrastructure projects’ overall adaptation and safety strategy. This study explores the benefits of BIM in railway infrastructure management and addresses the limitations of 6D BIM applications within the railway sector. A targeted case study presents the practical application of integrating the 6D BIM model and digital twins in this research.

3. Methodology

This study seeks to showcase the essential techniques for developing a 6D BIM model for the Metro Rail Transit (MRT) in Taipei, Taiwan, a railway tunnel of interest. The research conducted by Kaewunruen et al. [2] focused mainly on enhancing maintenance, which serves as the case study in this project. This study will further consider the elements of climate change adaptation and the implementation of BIM for its life cycle management.

This methodology has been further established considering the rail adapt framework [30,31]. The framework contains two main parts: developing an adaptation strategy and the implementation of a circular asset management plan [30]. For existing infrastructure to develop an adaptation strategy, a climate analysis and risk assessment are essential to create appropriate solutions for the identified hazards of climate change. A proper implementation plan is then required to ensure the successful delivery of these strategies, which can be enhanced with the application of BIM. Figure 1 below illustrates the comprehensive circularity of risk assessment in the railway sector, emphasizing the life cycle of adaptive, value-based circular railway asset management [31]. This holistic circularity incorporates various phases in the risk assessment process. Initially, potential risks and hazards are identified and categorized into different levels based on situational factors. In the functional analysis stage, relevant standards and practice guidelines are integrated to ensure system availability. Once all potential risks are identified, a vulnerability assessment is conducted to evaluate the system’s susceptibility, influenced by social, economic, and environmental factors [32]. Adaptive strategies and preventive solutions are then developed, analysing system vulnerabilities and uncertainties, followed by real-time monitoring to maintain control. Meanwhile, asset management is strategically organized and executed based on observed uncertainties, ensuring proactive monitoring and continual system updates.

The following methodologies present the adaptive asset management framework, divided into two main parts: adaptation strategies and an implementation plan. These sections focus on critical components relevant to this study, aiming to incorporate circularity and actionable adaptation solutions. The first part, adaptation strategies, introduces the case study locations, Chiang Kai-shek Memorial Hall Station and Dongmen Station on the Taipei Metro, and identifies potential risks through risk and hazard assessments. Critical components of the rail system in this case study are grouped into three categories: tunnel, track, and drainage systems, followed by the classification of corresponding prevention strategies. The second part of the implementation plan focuses on selecting appropriate BIM toolsets to develop a digital twin system. In this phase, a 3D model of the case study is created in Autodesk Revit for detailed analysis, while material property information is generated using Ansys Granta EduPack v.2021 and the Eco Audit Tool to support sustainable asset analysis.

3.1. Part 1: Adaptation Strategy

3.1.1. Background Information and Climate Study

The Tamsui–Xinyi line, also known as the Red Line, is a high-capacity metro system and is currently the longest line operated by Taipei Metro. This study concentrates on the underground section of the MRT, specifically, the arched route between Chiang Kai-shek Memorial Hall Station and Dongmen Station (Figure 2). Based on the project information provided by Taipei Metro, the underground section is termed the CK570H section [33], and the tunnel railway is estimated to be 32 metres below ground level and 1300 m long [2].

Taiwan experiences a subtropical climate, where summers can be scorching and humid. According to Cooper [34], government figures suggest that the temperature in Taiwan has increased by double the standard rate experienced worldwide. In addition, Yang [35] reported that the seas around Taiwan are rising at twice the global average, mainly due to its location. Being located on the seismic belt distribution, Taiwan is also prone to the extremes of typhoons or earthquakes that result in natural hazards, such as flooding, landslides, drought, and extreme heat. These natural hazards were specified as the most commonly seen risks of Taiwan’s changing climate [36]. Lin et al. [37] stated that current climate reduction measures have been able to refine the resilience of Taiwan. However, it concludes that there is the need for a more integrated effort to facilitate long-term strategies, including stakeholder collaboration.

3.1.2. Potential Impacts and Adaptation Strategies

The climate study indicates that Taiwan faces a range of weather-related impacts that need to be considered to avoid its consequences. Due to the CK570H section being underground (shown in Figure 3), it is barely affected by external conditions such as heavy rainfall and strong winds. However, these elements of climate change are associated with the extreme events commonly found in railway tunnels. These risks include flooding and drainage problems, leading to increased stress on the railway system [26]. Other indirect disasters that may cause flooding are earthquakes and rising sea levels, causing disruption of operations and damaging the infrastructure. Additionally, temperature variations could significantly affect the structural integrity of railway assets and its passengers and staff. Different temperature levels may cause the deterioration of the railway tunnel components and discomfort for the users [29].

Table 3. The proposed adaptation strategies for CK570H.

Rank	Main Risk	Adaption Strategies	Source
1	Flooding Water Infiltration	Install pump drainage systems	[35,36,37,38,39,40,41,42,43,44,45]
		Apply waterproof membrane layer	[43]
		Reinforce track embankments	[46,47]
2	Earthquake Ground Vibration	Utilise floating slab base isolation	[46,47]
		Apply track damping systems	[42,43]
		Install derailment prevention guards	[47]
		Reinforce structure lining	[47]
3	High Temperature Heat Stress Humidity	Implement tunnel cooling systems	[30,48,49]
4	Low Temperature Flash Freezing	Implement tunnel heating systems	[41,50]

highlights the proposed adaptation strategies to mitigate climate change issues, focusing on its infrastructure. As specified by DfT [38], infrastructural resilience can be achieved by strengthening the critical aspects of a system.

A number of different adaptation strategies explicitly developed for CK570H are found to be associated with certain parts of the railway tunnel. These measures are then grouped according to the infrastructural change on the main components of the MRT (tunnel, track, and system). The diversity of materials used in this project is also identified for each strategy, as outlined in

Table 4. List of materials for each component.

Group	Strategy	Material
Tunnel	Waterproof Membrane	Polyurethane
	Reinforced Layer	Concrete
	Temperature Regulator	Polyethylene
Track	Floating Slab Track	Concrete
	Damping Systems	Silicone Rubber
	Derailment Guards	Carbon Steel
Drainage System	Drainage Pipe	Polyvinylchloride
	Sump Pump	Cast Iron
	Sump Pit	Concrete

, which will be essential for the next stage of this framework. The focus is on three groups: the underground tunnel, the rail track, and the drainage system, which are all significantly affected by the weather impacts observed in the abovementioned climate impacts review for this practical study. The actions are traceable with material passports and the components’ usage data to enhance asset circularity at the end of service life.

3.2. Part 2: Implementation Plan

3.2.1. Digital Project Simulation and Strategy

The implementation of BIM starts with developing the MRT system’s 3D model using the software Autodesk Revit v.2021 based on its project information. A digital representation of the existing MRT is generated via Revit v.2021, and the addition of adaptation strategies is simulated into the 3D model. The virtual modelling of Revit allows unlimited design layers for the current infrastructure, further assessing the suitability of these measures with careful consideration. Figure 4 below presents the 3D model of the CK570H section using Revit.

After creating a 3D model, BIM integrates the time dimension (4D) by importing the Revit file into Navisworks Manage v.2021, software that can construct the optimal schedule for executing these adaptation strategies. A Microsoft 2021 Excel spreadsheet further simplifies this process, as the planning information can be extracted. Import the 3D model into Navisworks and integrate it with the process schedule to analyse virtual model information to support stakeholders and engineers in further adjustments if any clashes are spotted.

3.2.2. Valuation of Cost and Greenhouse Gas Emissions

This section estimates cost expenditures and greenhouse gas emissions for each material used, utilizing the material properties database and the Eco Audit Tool within Ansys Granta EduPack v.2021. The assessment measures costs and carbon emissions associated with specific railway system components, including the tunnel, rail track, and drainage systems, evaluated at each life cycle stage, from raw material extraction to end-of-life disposal. In addition, the cost and carbon consumption referred to in the measurements can be calculated using the provided Revit information and the software Ansys Granta EduPack v.2021, a complete database on material properties. This software features an extensive inventory of the materials available for infrastructure projects (Figure 5).

Table 5. Material data generated in Ansys Granta EduPack v.2021.

Material	Density (kg/m3)	Cost/kg (£)	CO2e/kg
Polyurethane	1200	0.60	3.21
Concrete	2400	0.04	0.11
Carbon Steel	7800	0.53	2.38
Polyethylene	950	1.04	1.86
Stainless Steel	7740	2.13	5.45
Silicone Rubber	1120	2.89	6.52
Polyvinylchloride	1375	1.34	2.7
Cast Iron	6860	0.23	2.38

presents the prominent figures for each material used in this study: density, cost, and greenhouse gas emissions. These figures will be available for further measurements of sustainability and cost expenditure.

For 6D BIM, the carbon footprint will be assessed through the estimation of greenhouse gas (GHG) emissions to achieve sustainable analysis throughout a project’s life cycle. The carbon footprint of each component (floating slab track, waterproof membrane, drainage pump system, etc.) in the project can be calculated using the Eco Audit Tool, which is accessible in Granta EduPack v.2021. This resource enables measurement of the total carbon footprint of each component, issuing a detailed analysis that clarifies the total estimation (Figure 6).

It should be noted that the average values used do not necessarily depict accurately the emissions linked to construction materials used on the job site. Depending on the cement type used and the production route for carbon steel, the linked emissions can vary, but for a first assessment, the use of average emissions is acceptable.

4. Results

4.1. Virtual Simulation and Project Scheme

The 3D model of the MRT has been developed in Revit v.2021 based on measurements from the existing model in the previous study by Kaewunruen et al. [2]. The flexibility of Revit v.2021 allows for real-time updates to the model and additional design modifications depending on the requirements. This study enhances the model by analysing the detailed design of the tunnel and adding the elements of the proposed measures. Figure 7 demonstrates the components of the detailed tunnel design in this case study. This detailed modelling solution allows the users to visualise the project before the actual construction. Revit facilitates material decisions that can be used for all the design components created, and this feature is also reflected in the simulation.

The 3D BIM model supports the structural analysis in proper assembly planning for the MRT during the complex infrastructure modification design. These alterations are designed precisely through virtual modelling, as presented in Figure 8. The floating slab tracks (FST) are considered the primary adjustment for the MRT, measuring 3490 mm in length and 2622 mm in width; it required accuracy in design (shown in Figure 9). The FST functions with the dampers on the sides and bottom of the concrete slab and the derailment guards above, and the FST benefits sustainable management in energy due to lower vibration and noise during operation. It is worth noting that any changes to these components can be done in Revit, allowing limitless design possibilities.

Following the completion of an immersive 3D BIM model, Revit provides data for each component of the adaptation strategies included in the model. Figure 10 shows a bill of quantities (BOQ) of the components used in this project by Revit; the fundamental information is well managed, and the 5D BIM implementation is considered for estimating costs.

The dimension of time (4D BIM) for an adaptation strategy project is evaluated by producing a strategic action plan for the works involved. These construction activities are arranged in an Excel spreadsheet and imported into Navisworks and the Revit model to maximise the success rate. Navisworks exhibits another form of virtual modelling of the new MRT. It features the tool for clash detection within the model, identifying for the users even the slightest issues in the design. Figure 11 shows the outcome of a proper project scheme generated in Navisworks. This tool enables the users to control the project delivery and assists labour organisations within the construction team. Based on the results, some events co-occur, such as demolishing the existing tunnel frame and constructing the floating slab tracks. This is mainly because the manufacturing of these concrete slabs is fabricated off-site and can be produced while construction works are in progress. In addition, Navisworks’s 4D BIM scheduling provides a video simulation of these construction processes to clarify the project scheme arrangement.

4.2. Measurement of Additional Costs

The 5D perspective of this project involves estimating costs resulting from the developed strategies. Integrating the software Ansys Granta Edupack v.2021, the properties of each material are determined through its estimated values, listed in Table 5. However, the units of these values are in kilograms (kg), indicating the need to calculate the density of each component. This is done by multiplying the volume of the element with the material density from Table 5. As mentioned above, Revit can present the volume of a designed component in BOQ form. These figures are collected from Revit and applied to quantify the mass of each element. This is then registered in

Table 6. Calculated volume and mass for each component.

Group	Strategy	Volume (m3)	Mass (kg)
Tunnel	Waterproof Membrane	0.20	240
	Reinforced Layer	4.69	11256
	Temperature Regulator	0.12	114
Track	Floating Slab Track	1.17	2808
	Damping Systems	0.014	15.68
	Derailment Guards	0.01	78
System	Drainage Pipe	0.07	96.25
	Sump Pump	0.008	54.88
	Sump Pit	0.09	216

. It is also important to note that these values relate to a 1-metre length of the tunnel.

Table 7. Measurement of costs for the adaptation strategies.

Group	Strategy	Cost (£)	Quantity	Total (£)
Tunnel	Waterproof Membrane	144	1	712.8
	Reinforced Layer	450.24	1
	Temperature Regulator	118.56	1
Track	Floating Slab Track	112.32	1	376.28
	Damping Systems	45.32	4
	Derailment Guards	41.34	2
System	Drainage Pipe	128.98	1	150.24
	Sump Pump	12.62	1
	Sump Pit	8.64	1
				1239.32

breaks down the calculation of additional costs following these infrastructural changes to the railway tunnel. The results show that the estimated costs for these adaptive measures on the MRT’s tunnel, track, and system are £712.8, £376.28, and £150.24, respectively. The most significant asset in the study is the new tunnel layer made of reinforced concrete. For every metre of the railway tunnel, the cost of changes is £1239.32. Based on the fundamental information of the length of the CK570H section, which is 1300 metres, establishing these strategies for the whole system will be £1,611,116. Although the required adaptation to climate change is costly, this improvement will be advantageous throughout the life span of the infrastructure due to its high efficiency against weather hazards. Additionally, these adjustments aim to reduce the cost of maintenance and ultimately increase the safety and reliability of the railway tunnel in countering the future of climate change.

4.3. Estimation of Greenhouse Gas Emissions

By fully utilising the software Ansys Granta EduPack v.2021, the Eco Audit Tool contributes a complete carbon footprint assessment of the adaptation strategy. This study uses the tool to estimate the materials and manufacturing emissions. Figure 12 displays the Eco Audit Report resulting from the input of the material information (Figure 6) for each element of the changes. This may be extended to include transport, utilisation, and disposal emissions to incorporate a full report regarding the carbon footprint from these additional measures. For infrastructure projects, the majority of the overall emissions is linked to the carbon footprint of the construction materials (embodied carbon).

Table 8. Estimation of GHG emissions for the adaptation strategies.

Group	Strategy	CO2e (kg)	Total (kg)	%
Tunnel	Waterproof Membrane	450	2120	58.16
	Reinforced Layer	1300
	Temperature Regulator	370
Track	Floating Slab Track	320	1100	30.18
	Damping Systems	410
	Derailment Guards	370
System	Drainage Pipe	270	425	11.66
	Sump Pump	130
	Sump Pit	25
		Total	3645	100

breaks down the estimation of GHG emissions for each component. The emissions (kgCO₂e) of each material used is multiplied by the mass of the element, generating the amount of GHG emissions from that component. The results show that the estimated carbon footprint of these MRT changes on the tunnel, track, and system are 2120 kg (58.16%), 1100 kg (30.18%), and 425 kg (11.66%), respectively. Similar to 5D, the values for 6D are equal to the 1-metre length of the railway tunnel. The total carbon footprint of these infrastructure changes is approximately 4,738,500. Although these values are estimates, implementing adaptation strategies distributes high carbon emissions. Therefore, there is a need to innovate sustainable adaptations that can be more efficient in both responding to and reducing the industry’s impact on climate change. The ability to estimate GHG emissions concludes the development of 6D BIM for the new MRT in its potential for climate change adaptation.

5. Discussion and Future Research Direction

The capabilities of BIM have already been known to revolutionise infrastructure design and management in industry. The potential of BIM can help achieve the goal of sustainability when constructing climate change adaptations for railway tunnels. Furthermore, it enables the successful strategic adoption of these measures. Revit facilities for 3D representation aid the project team and involve the stakeholders in designing and visualising the infrastructural changes to be added or adjusted. It provides collaborative and suitable planning for the modifications to improve railway resilience. By integrating the 3D model with Navisworks, the project is coordinated according to the time constraints, ensuring that 4D is achieved and every perspective of the tunnel development is completed with a high quality before completion. 5D and 6D revolve around the software Ansys Granta EduPack v.2021, a critical application for estimating the additional costs and GHG emissions. Incorporating the data of the materials and their performance is a valuable asset for the stakeholders when optimising material selection, the carbon footprint, and its resistance to changing climate conditions. Using Environmental Product Declarations (EPDs) allows the users to further refine the 6D BIM analysis, as they describe the environmental impacts of the products used more accurately. As the embodied carbon is of highest importance for the overall sustainability of the project, BIM allows the users to analyse variants with steel and concrete with low GHG emissions. Using low carbon materials may reduce the overall carbon footprint drastically.

These multidimensional abilities of BIM continue to improve the project management processes and are helpful for future development plans like adaptation to climate change. It is also worth noting that BIM implementation for adapting railway tunnels to climate change has significant environmental and economic benefits. Early designing of solutions minimises construction modification costs, leading to the use of BIM for optimal material sourcing, project delivery, and energy consumption. It promotes a more sustainable approach to the traditional infrastructure management methods in the industry. It aligns with sustainability goals, ensuring railway tunnels can maintain and operate despite climate challenges.

It is important to note that the adaptation strategies in this study are uniquely tailored to this specific case. Certain climate factors identified in broader studies, such as windstorms, are irrelevant here and have been excluded; instead, the strategies are customized to the local climate conditions. Advanced BIM technologies offer potential solutions to this limitation by enabling robust collaboration, supporting efficiently designed, context-specific adaptation strategies and facilitating the development of new implementation plans tailored to diverse environmental conditions. Future research is needed to advance the integration of large-scale digital tools further, enhancing the practicality and scalability of these strategies. Another significant concern is the ongoing expansion of the railway system and increasing digitalisation, which introduce complexities in data management and create challenges for sustainability and decarbonization efforts. Managing diverse data, such as integrating new datasets with historical records and ensuring seamless data exchange without information loss, remains a critical issue requiring resolution [51]. Issues with data interchange and inconsistent data formats reduce asset management efficiency within the system. Further research is recommended to explore solutions for enhancing system interoperability, aiming to improve robustness and operational efficiency.

In summary, BIM is an effective approach for designing and analysing the structure of a project. However, there are certain limitations and challenges that need to be addressed to ensure its success. One such challenge is the reliability of climate data used in the study (e.g., [43]); the data and conducted strategies can thus be tailor-made for different cases. Any inaccurate information could affect the success of the adaptive measures, as they depend on up-to-date climate studies. It is recommended that the predictive tools established by government sectors worldwide be utilised. The tools precisely anticipate future climate projections, which will help enhance the development of these adaptation strategies.

6. Conclusions

It has been reported that adaptation measures are necessary to ensure the safety and security of railways in the face of climate change. Incorporating technological innovations like BIM can help make railway infrastructure resilient. This particular study has demonstrated that the implementation of BIM significantly improves the efficiency of project management for railway tunnels in its aim to adapt to climate change. When conducting a detailed study on the Tamsui–Xinyi Line located in Taipei, identifying risks and potential impacts in the context of its climate has been essential in developing specific adaptation strategies for the CK570H section. Although built underground, the railway tunnel is still affected by the changing climate conditions, which require infrastructure modifications. BIM is the leading solution to manage this challenge through comprehensive 3D to 6D approaches. These results show that BIM can manage the entire life cycle of the railway tunnel adaptation project of the Tamsui–Xinyi Line, beginning from its initial design stages. It demonstrates enhanced decision-making in design, organisation of labour, and estimation of cost and sustainability factors related to the additional changes. BIM looks to elevate the adaptation process, and this dynamic approach is a technological advancement and a strategic move forward for developing resilient transportation networks in the future industry.

Rail transit infrastructure encompasses a range of complex, interconnected components, including rail tracks, station embankments, electrical control systems, and rolling stock. The diverse information modelling tools within BIM technology facilitate a comprehensive analysis across various task groups within the railway system throughout its entire life cycle [52]. Future research should focus on enhancing the integration of large-scale digital toolkits within BIM models for railway systems and developing solutions to minimize information loss during data exchanges.